Optical receiver

ABSTRACT

An optical receiver is disclosed, including an optoelectronic detector, a transimpedance amplification (TIA) circuit, a single-ended-to-differential converter, an I/O interface, and a controller. The optoelectronic detector, having bandwidth lower than required system transmission bandwidth, converts an optical signal into a current signal. The TIA circuit compensate gain for the received current signal based on a received control signal, to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector. The single-ended-to-differential converter converts the voltage signal into a differential voltage signal. The I/O interface outputs the differential voltage signal. The controller generates the control signal based on the differential voltage signal. The optical receiver disclosed can reduce costs while ensuring signal quality.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/520,029, filed on Jul. 23, 2019, which is a continuation ofInternational Application No. PCT/CN2017/072513, filed on Jan. 24, 2017.All of the afore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

This application relates to the optical communications field, and inparticular, to an optical receiver having a high-frequency peak gain.

BACKGROUND

10G passive optical network (PON) technologies and products have beenready and enter a large-scale deployment stage. In a 10G PON, costs ofan optical network unit (ONU) become a key problem in massive deploymentin the future, and costs reduction is a key requirement of the 10G PON.A bi-directional optical sub-assembly on board (BOB) technology that iswidely used in a gigabit passive optical network (GPON) can also be usedin the 10G PON, to reduce packaging costs. Therefore, component costsreduction is key to further costs reduction.

In the ONU of the 10G PON, a 10G avalanche photodiode (APD) is ahighest-rate optical component, and accounts for a largest proportion ofcosts. Therefore, reduction of costs of the APD is key to reduction ofthe costs of the ONU of the 10G PON.

SUMMARY

Embodiments of this application provide an optical receiver, to receivea high-rate signal by using a low-rate APD, thereby resolving a problemthat costs of an overall component are excessively high due toexcessively high costs of a high-rate APD.

According to a first aspect, an optical receiver is provided, includingan optoelectronic detector, a transimpedance amplification circuit, asingle-ended-to-differential converter, an I/O interface, and acontroller, where the optoelectronic detector is configured to convert areceived optical signal into a current signal, where bandwidth of theoptoelectronic detector is lower than a system transmission bandwidthrequirement; the transimpedance amplification circuit is configured to:receive the current signal and a first control signal, and performtransimpedance gain on the current signal based on the first controlsignal, to obtain a voltage signal, where a frequency response value ofthe current signal within first bandwidth is greater than that withinthe bandwidth of the optoelectronic detector, and any frequency in thefirst bandwidth is not lower than an upper cut-off frequency of theoptoelectronic detector; the single-ended-to-differential converter isconfigured to: convert the voltage signal into a differential voltagesignal, and send the differential voltage signal to the I/O interfaceand the controller; the I/O interface is configured to output thedifferential voltage signal; and the controller is configured to:generate a second control signal based on the differential voltagesignal, and send the second control signal to the transimpedanceamplification circuit, where the second control signal is used tocontrol the transimpedance amplification circuit to performtransimpedance gain on the current signal.

According to the optical receiver provided in this embodiment of thisapplication, the optoelectronic detector whose bandwidth is lower thanthe system transmission bandwidth requirement is used, to greatly reducecosts of the optical receiver; and the transimpedance amplificationcircuit is used, to remedy received signal deterioration caused bybandwidth insufficiency, so that component costs are reduced whilereceived signal quality is ensured.

With reference to the first aspect, in a first possible implementationof the first aspect, the controller is specifically configured to:perform a plurality of times of sampling processing, and perform thefollowing process in each time of sampling processing: sending a controlsignal to the transimpedance amplification circuit; sampling an upperlevel and a lower level of the received differential voltage signal, toobtain a value of a sampling point and modifying the control signalbased on a preset modification amount; and after performing theplurality of times of sampling processing, the controller isspecifically configured to use, as the second control signal, a controlsignal corresponding to a sampling point with a maximum value in aplurality of sampling points obtained after the plurality of times ofsampling processing.

With reference to the first aspect, in a second possible implementationof the first aspect, the controller is specifically configured to:perform a plurality of times of detection processing, and perform thefollowing process in each time of detection processing: sending acontrol signal to the transimpedance amplification circuit; using afirst frequency as a boundary, and separately detecting energy of thedifferential voltage signal that is higher than the first frequency andenergy of the differential voltage signal that is lower than the firstfrequency, to obtain an energy difference, where the first frequency is0.28/Tb, and Tb is duration of each bit of the differential voltagesignal; and modifying the control signal based on a preset modificationamount; and after performing the plurality of times of detectionprocessing, the controller is specifically configured to use, as thesecond control signal, a control signal corresponding to a minimumenergy difference in a plurality of energy differences obtained afterthe plurality of times of detection processing.

The foregoing two embodiments are two implementations in which thecontroller selects an optimal control signal. The optimal control signalcan enable the transimpedance amplification circuit to perform, for theoptoelectronic detector, optimal compensation that can be implemented bythe transimpedance amplification circuit. Further, gain compensation bythe transimpedance amplification circuit is implemented inside thetransimpedance amplification circuit, so that no additional noise isintroduced.

With reference to the first aspect, in a third possible implementationof the first aspect, the optical receiver further includes an equalizer,where the equalizer is configured to: receive the differential voltagesignal and a third control signal, perform gain on the differentialvoltage signal based on the third control signal, and send adifferential voltage signal obtained after the gain to the controllerand the I/O interface, where a frequency response value of thedifferential voltage signal within second bandwidth is greater than thatwithin the first bandwidth, and any frequency in the second bandwidth ishigher than any frequency in the first bandwidth; and the controller isfurther configured to: generate a fourth control signal based on thedifferential voltage signal, and send the fourth control signal to theequalizer, where the fourth control signal is used to control theequalizer to perform gain on the differential voltage signal.

In this embodiment of this application, the equalizer is used, so that arange of compensation for the optoelectronic detector is extended, andgain compensation can be performed for a higher frequency compared withthe transimpedance amplification circuit.

With reference to the third possible implementation of the first aspect,in a fourth possible implementation of the first aspect, the controlleris specifically configured to: perform a plurality of times of firstsampling processing, and perform the following process in each time offirst sampling processing: sending a control signal to thetransimpedance amplification circuit; sampling an upper level and alower level of the received differential voltage signal, to obtain avalue of a sampling point; and modifying the control signal based on apreset modification amount; and after performing the plurality of timesof first sampling processing, the controller is specifically configuredto use, as the second control signal, a control signal corresponding toa sampling point with a maximum value in a plurality of sampling pointsobtained after the plurality of times of first sampling processing; and

after sending the second control signal to the transimpedanceamplification circuit, the controller further performs a plurality oftimes of second sampling processing, and performs the following processin each time of second sampling processing: sending a control signal tothe equalizer, sampling an upper level and a lower level of the receiveddifferential voltage signal, to obtain a value of a sampling point; andmodifying the control signal based on the preset modification amount;and after performing the plurality of times of second samplingprocessing, the controller is specifically configured to use, as thefourth control signal, a control signal corresponding to a samplingpoint with a maximum value in a plurality of sampling points obtainedafter the plurality of times of second sampling processing.

With reference to the third possible implementation of the first aspect,in a fifth possible implementation of the first aspect, the controlleris specifically configured to: perform a plurality of times of firstdetection processing, and perform the following process in each time offirst detection processing: sending a control signal to thetransimpedance amplification circuit; using a first frequency as aboundary, and separately detecting energy of the differential voltagesignal that is higher than the first frequency and energy of thedifferential voltage signal that is lower than the first frequency, toobtain an energy difference, where the first frequency is 0.28/Tb, andTb is duration of each bit of the differential voltage signal, andmodifying the control signal based on a preset modification amount; andafter performing the plurality of times of first detection processing,the controller is specifically configured to use, as the second controlsignal, a control signal corresponding to a minimum energy difference ina plurality of energy differences obtained after the plurality of timesof first detection processing; and

after sending the second control signal to the transimpedanceamplification circuit, the controller further performs a plurality oftimes of second detection processing, and performs the following processin each time of second detection processing: sending a control signal tothe equalizer; using the first frequency as a boundary, and separatelydetecting energy of the differential voltage signal that is higher thanthe first frequency and energy of the differential voltage signal thatis lower than the first frequency, to obtain an energy difference, wherethe first frequency is 0.28/Tb, and Tb is duration of each bit of thedifferential voltage signal; and modifying the control signal based onthe preset modification amount; and after performing the plurality oftimes of second detection processing, the controller is specificallyconfigured to use, as the fourth control signal, a control signalcorresponding to a minimum energy difference in a plurality of energydifferences obtained after the plurality of times of second detectionprocessing.

The foregoing two embodiments are two manners in which the controllerselects an optimal control signal when the optical receiver includes theequalizer. The transimpedance amplification circuit is first used toperform gain compensation without introducing additional noise; and ifgain compensation is not enough, the equalizer is then used to performgain compensation, so that an optimal compensation effect is achieved ata minimum noise cost.

According to a second aspect, an optical receiver is provided, includingan optoelectronic detector, a first transimpedance amplificationcircuit, a single-ended-to-differential converter, an equalizer, an I/Ointerface, and a controller, where the optoelectronic detector isconfigured to convert a received optical signal into a current signal,where bandwidth of the optoelectronic detector is lower than a systemtransmission bandwidth requirement; the first transimpedanceamplification circuit is configured to: receive the current signal, andperform transimpedance gain on the current signal, to obtain a voltagesignal; the single-ended-to-differential converter is configured to:convert the voltage signal into a differential voltage signal, and sendthe differential voltage signal to the equalizer; the equalizer isconfigured to: receive the differential voltage signal and a firstcontrol signal, perform gain on the differential voltage signal based onthe first control signal, and send a differential voltage signalobtained after the gain to the I/O interface and the controller, where afrequency response value of the differential voltage signal within firstbandwidth is greater than that within the bandwidth of theoptoelectronic detector, and any frequency in the first bandwidth ishigher than an upper cut-off frequency of the optoelectronic detector;the I/O interface is configured to output the differential voltagesignal obtained after the gain; and the controller is configured to:generate a second control signal based on the differential voltagesignal obtained after the gain, and send the second control signal tothe equalizer, where the second control signal is used to control theequalizer to perform gain on the differential voltage signal.

In this embodiment of this application, the equalizer is used toimplement gain compensation for a high frequency. According to a featureof a wide compensation range of the equalizer, the equalizer is enabledto perform compensation for the optoelectronic detector, to achieve anoptimal effect. Compared with the embodiment provided in the firstaspect, this embodiment has an advantage of a wider range ofcompensation for the optoelectronic detector, and has a disadvantagethat more noise is introduced because gain compensation for the highfrequency is completely implemented by the equalizer.

With reference to the second aspect, in a first possible implementationof the second aspect, the controller is specifically configured to:perform a plurality of times of sampling processing, and perform thefollowing process in each time of sampling processing: sending a controlsignal to the equalizer; sampling an upper level and a lower level ofthe received differential voltage signal, to obtain a value of asampling point; and modifying the control signal based on a presetmodification amount; and after performing the plurality of times ofsampling processing, the controller is specifically configured to use,as the second control signal, a control signal corresponding to asampling point with a maximum value in a plurality of sampling pointsobtained after the plurality of times of sampling processing.

With reference to the second aspect, in a second possible implementationof the second aspect, the controller is specifically configured to:perform a plurality of times of detection processing, and perform thefollowing process in each time of detection processing: sending acontrol signal to the equalizer; using a first frequency as a boundaryand separately detecting energy of the differential voltage signal thatis higher than the first frequency and energy of the differentialvoltage signal that is lower than the first frequency, to obtain anenergy difference, where the first frequency is 0.28/Tb, and Tb isduration of each bit of the differential voltage signal; and modifyingthe control signal based on a preset modification amount; and afterperforming the plurality of times of detection processing, thecontroller is specifically configured to use, as the second controlsignal, a control signal corresponding to a minimum energy difference ina plurality of energy differences obtained after the plurality of timesof detection processing.

According to a third aspect, a receiving method is provided, including:converting, by an optical receiver, a received optical signal into acurrent signal by using an optoelectronic detector, where bandwidth ofthe optoelectronic detector is lower than a system transmissionbandwidth requirement; performing, by the optical receiver,transimpedance gain on the current signal based on a first controlsignal, to obtain a voltage signal, where a frequency response value ofthe current signal within first bandwidth is greater than that withinthe bandwidth of the optoelectronic detector, and any frequency in thefirst bandwidth is not lower than an upper cut-off frequency of theoptoelectronic detector; and converting, by the optical receiver, thevoltage signal into a differential voltage signal, and generating asecond control signal based on the differential voltage signal, wherethe second control signal is used to control the optical receiver toperform transimpedance gain on the current signal.

With reference to the third aspect, in a first possible implementationof the third aspect, the generating a second control signal based on thedifferential voltage signal specifically includes: performing aplurality of times of sampling processing, and using, as the secondcontrol signal, a control signal corresponding to a sampling point witha maximum value in a plurality of sampling points obtained after theplurality of times of sampling processing, where the following processis performed in each time of sampling processing: performingtransimpedance gain on the current signal based on a control signal, toobtain the voltage signal, and converting the voltage signal into thedifferential voltage signal; sampling an upper level and a lower levelof the differential voltage signal, to obtain a value of a samplingpoint; and modifying the control signal based on a preset modificationamount.

With reference to the third aspect, in a second possible implementationof the third aspect, the generating a second control signal based on thedifferential voltage signal specifically includes: performing aplurality of times of detection processing, and using, as the secondcontrol signal, a control signal corresponding to a minimum energydifference in a plurality of energy differences obtained after theplurality of times of detection processing, where the following processis performed in each time of detection processing: performingtransimpedance gain on the current signal based on a control signal, toobtain the voltage signal, and converting the voltage signal into thedifferential voltage signal; using a first frequency as a boundary, andseparately detecting energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency, to obtain an energydifference, where the first frequency is 0.28/Tb, and Tb is duration ofeach bit of the differential voltage signal; and modifying the controlsignal based on a preset modification amount.

With reference to the third aspect, in a third possible implementationof the third aspect, after the converting, by the optical receiver, thevoltage signal into a differential voltage signal, the method furtherincludes: performing gain on the differential voltage signal based on athird control signal, where a frequency response value of thedifferential voltage signal within second bandwidth is greater than thatwithin the first bandwidth, and any frequency in the second bandwidth ishigher than any frequency in the first bandwidth; and after thegenerating a second control signal, the method further includes:generating a fourth control signal based on a differential voltagesignal obtained after the gain, where the fourth control signal is usedto control the optical receiver to perform gain on the differentialvoltage signal.

With reference to the third possible implementation of the third aspect,in a fourth possible implementation of the third aspect, the generatinga second control signal based on the differential voltage signalspecifically includes: performing a plurality of times of first samplingprocessing, and using, as the second control signal, a control signalcorresponding to a sampling point with a maximum value in a plurality ofsampling points obtained after the plurality of times of first samplingprocessing, where the following process is performed in each time offirst sampling processing: performing transimpedance gain on the currentsignal based on a control signal, to obtain the voltage signal, andconverting the voltage signal into the differential voltage signal;sampling an upper level and a lower level of the differential voltagesignal, to obtain a value of a sampling point; and modifying the controlsignal based on a preset modification amount; and the generating afourth control signal based on the differential voltage signalspecifically includes: performing a plurality of times of secondsampling processing, and using, as the fourth control signal, a controlsignal corresponding to a sampling point with a maximum value in aplurality of sampling points obtained after the plurality of times ofsecond sampling processing, where the following process is performed ineach time of second sampling processing: performing gain on thedifferential voltage signal based on a control signal, to obtain thedifferential voltage signal obtained after the gain; sampling an upperlevel and a lower level of the differential voltage signal obtainedafter the gain, to obtain a value of a sampling point; and modifying thecontrol signal based on the preset modification amount.

With reference to the third possible implementation of the third aspect,in a fifth possible implementation of the third aspect, the generating asecond control signal based on the differential voltage signalspecifically includes: performing a plurality of times of firstdetection processing, and using, as the second control signal, a controlsignal corresponding to a minimum energy difference in a plurality ofenergy differences obtained after the plurality of times of firstdetection processing, where the following process is performed in eachtime of first detection processing: performing transimpedance gain onthe current signal based on a control signal, to obtain the voltagesignal, and converting the voltage signal into the differential voltagesignal; sampling an upper level and a lower level of the differentialvoltage signal, to obtain a value of a sampling point; and modifying thecontrol signal based on a preset modification amount; and the generatinga fourth control signal based on the differential voltage signalspecifically includes: performing a plurality of times of seconddetection processing, and using, as the fourth control signal, a controlsignal corresponding to a minimum energy difference in a plurality ofenergy differences obtained after the plurality of times of secondsampling processing, where the following process is performed in eachtime of second detection processing: performing gain on the differentialvoltage signal based on a control signal, to obtain the differentialvoltage signal obtained after the gain; using a first frequency as aboundary, and separately detecting energy of the differential voltagesignal that is higher than the first frequency and energy of thedifferential voltage signal that is lower than the first frequency, toobtain an energy difference, where the first frequency is 0.28/Tb, andTb is duration of each bit of the differential voltage signal; andmodifying the control signal based on the preset modification amount.

The embodiment in the third aspect is a receiving method correspondingto the optical receiver in the first aspect, beneficial effects are thesame as those of the first aspect, and details are not described hereinagain.

According to a fourth aspect, a receiving method is provided,comprising: converting, by an optical receiver, a received opticalsignal into a current signal by using an optoelectronic detector, wherebandwidth of the optoelectronic detector is lower than a systemtransmission bandwidth requirement; performing, by the optical receiver,transimpedance gain on the current signal, to obtain a voltage signal,and converting the voltage signal into a differential voltage signal;performing, by the optical receiver, gain on the differential voltagesignal based on a first control signal, to obtain a differential voltagesignal obtained after the gain, where a frequency response value of thedifferential voltage signal within first bandwidth is greater than thatwithin the bandwidth of the optoelectronic detector, and any frequencyin the first bandwidth is higher than an upper cut-off frequency of theoptoelectronic detector; and generating, by the optical receiver, asecond control signal based on the differential voltage signal obtainedafter the gain, where the second control signal is used to control theoptical receiver to perform gain on the differential voltage signal.

With reference to the fourth aspect, in a first possible implementationof the fourth aspect, the generating a second control signal based onthe differential voltage signal obtained after the gain specificallyincludes: performing a plurality of times of sampling processing, andusing, as the second control signal, a control signal corresponding to asampling point with a maximum value in a plurality of sampling pointsobtained after the plurality of times of sampling processing, where thefollowing process is performed in each time of sampling processing:performing gain on the differential voltage signal based on a controlsignal, to obtain the differential voltage signal obtained after thegain; sampling an upper level and a lower level of the differentialvoltage signal obtained after the gain, to obtain a value of a samplingpoint; and modifying the control signal based on a preset modificationamount.

With reference to the fourth aspect, in a second possible implementationof the fourth aspect, the generating a second control signal based onthe differential voltage signal obtained after the gain specificallyincludes: performing a plurality of times of detection processing, andusing, as the second control signal, a control signal corresponding to aminimum energy difference in a plurality of energy differences obtainedafter the plurality of times of detection processing, where thefollowing process is performed in each time of detection processing:performing gain on the differential voltage signal based on a controlsignal, to obtain the differential voltage signal obtained after thegain; using a first frequency as a boundary, and separately detectingenergy that is of the differential voltage signal obtained after thegain and that is higher than the first frequency and energy that is ofthe differential voltage signal obtained after the gain and that islower than the first frequency, to obtain an energy difference, wherethe first frequency is 0.28/Tb, and Tb is duration of each bit of thedifferential voltage signal, and modifying the control signal based on apreset modification amount.

The embodiment in the fourth aspect is a receiving method correspondingto the optical receiver in the second aspect, beneficial effects are thesame as those of the second aspect, and details are not described hereinagain.

According to a fifth aspect, a transimpedance amplification circuit isprovided, including a fixed resistor, a first transistor, a secondtransistor, a variable resistance circuit, and an output port, where thefixed resistor includes two ports, where one port is grounded, and theother port is connected to an emitter of the first transistor; a base ofthe first transistor is configured to receive an input signal, and acollector of the first transistor is connected to an emitter of thesecond transistor; a base of the second transistor is configured toreceive a bias voltage signal, and a collector of the second transistoris connected to a first port of the variable resistance circuit, wherethe bias voltage signal is used to adjust a gain for the input signal;the output port is located on a connecting line between the collector ofthe second transistor and the first port of the variable resistancecircuit; and the variable resistance circuit includes three ports, wherea second port of the variable resistance circuit is configured toreceive a control signal, a third port of the variable resistancecircuit is grounded, and the control signal is used to control aresistance value of the variable resistance circuit.

In conclusion, according to the optical receiver provided in theembodiments of this application, the optoelectronic detector whosebandwidth is lower than the system transmission bandwidth requirement isused, to greatly reduce costs of the optical receiver; and thetransimpedance amplification circuit is used, to remedy received signaldeterioration caused by bandwidth insufficiency, so that component costsare reduced while received signal quality is ensured.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of a 10G PON system;

FIG. 2 is a schematic structural diagram of an optical receiveraccording to an embodiment of this application:

FIG. 3 is a schematic structural diagram of a transimpedanceamplification circuit according to another embodiment of thisapplication;

FIG. 4 is a diagram of a frequency response curve of a transimpedanceamplification circuit according to another embodiment of thisapplication;

FIG. 5 is a schematic diagram of performing, by a transimpedanceamplification circuit, gain compensation for a high frequency of anoptoelectronic detector according to another embodiment of thisapplication:

FIG. 6 is schematic diagrams of under-compensation, optimalcompensation, and over-compensation:

FIG. 7 is a schematic structural diagram of an optical receiveraccording to another embodiment of this application:

FIG. 8 is a flowchart of a receiving method according to anotherembodiment of this application:

FIG. 9 is a schematic structural diagram of an optical receiveraccording to another embodiment of this application:

FIG. 10 is a flowchart of a receiving method according to anotherembodiment of this application; and

FIG. 11 is a schematic structural diagram of an optical receiveraccording to another embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes the technical solutions in the embodiments ofthis application with reference to the accompanying drawings in theembodiments of this application.

Referring to FIG. 1, FIG. 1 is a schematic structural diagram of a 10GPON system to which an ONU or an Optical Line Terminal (OLT) that has anoptical receiver provided in the embodiments of this application isapplicable. A 10G PON system 100 includes at least one OLT 110, aplurality of ONUs 120, and one optical distribution network (ODN) 130.The OLT 110 is connected to the plurality of ONUs 120 by using the ODN130 in a point-to-multipoint manner. A direction from the OLT 110 to theONU 120 is defined as a downlink direction, and a direction from the ONU120 to the OLT 110 is defined as an uplink direction.

An embodiment of this application provides an optical receiver 200, andthe optical receiver 200 may be applied to an ONU of a 10G PON system ora higher-rate PON system. As shown in FIG. 2, the optical receiver 200includes an optoelectronic detector 201, a transimpedance amplificationcircuit 202, a single-ended-to-differential converter 203, an I/Ointerface 204, and a controller 205.

The optoelectronic detector 201 is configured to convert a receivedoptical signal into a current signal, where bandwidth of theoptoelectronic detector 201 is lower than a system transmissionbandwidth requirement.

Specifically, the optoelectronic detector 201 accounts for a largestproportion of costs in the optical receiver 200, and therefore componentcosts can be greatly reduced by using the low-bandwidth optoelectronicdetector 201. Correspondingly, there is a problem that a high-frequencysignal cannot be detected.

The transimpedance amplification circuit 202 is configured to: receivethe current signal and a first control signal, and performtransimpedance gain on the current signal based on the first controlsignal, to obtain a voltage signal, where a frequency response value ofthe current signal within first bandwidth is greater than that withinthe bandwidth of the optoelectronic detector 201, and any frequency inthe first bandwidth is not lower than an upper cut-off frequency of theoptoelectronic detector 201.

Optionally, the transimpedance amplification circuit 202 may be anunderdamped transimpedance amplification circuit. This applicationprovides a possible implementation. A structure of the underdampedtransimpedance amplification circuit is shown in FIG. 3, and includes afixed resistor 301, a first transistor 302, a second transistor 303, avariable resistance circuit 304, and an output port 305.

The fixed resistor 301 includes two ports. One port is grounded, and theother port is connected to an emitter of the first transistor 302. Abase of the first transistor 302 is configured to receive an inputsignal, and a collector of the first transistor 302 is connected to anemitter of the second transistor 303. A base of the second transistor303 is configured to receive a bias voltage signal, and a collector ofthe second transistor 303 is connected to a first port of the variableresistance circuit 304. The bias voltage signal is used to adjust a gainfor the input signal. The output port 305 is located on a connectingline between the collector of the second transistor 303 and the firstport of the variable resistance circuit 304. The variable resistancecircuit 304 includes three ports. A second port of the variableresistance circuit 304 is configured to receive a control signal, athird port of the variable resistance circuit 304 is grounded, and thecontrol signal is used to control a resistance value of the variableresistance circuit 304.

It should be understood that 3041 in FIG. 3 shows a specificimplementation solution of the variable resistance circuit, and thereare still many similar implementation solutions. This is not limited inthis application.

In this embodiment of this application, the resistance value of thevariable resistance circuit 304 is adjusted, to change a damping factorof the transimpedance amplification circuit 202. A smaller dampingfactor brings a greater additional gain for a high frequency. Afrequency response curve of the transimpedance amplification circuit 202is shown in FIG. 4, and (in FIG. 4 is a damping factor. The highfrequency herein is a frequency higher than the upper cut-off frequencyof the optoelectronic detector 201.

It should be noted that the first bandwidth of the transimpedanceamplification circuit 202 may be controlled by using an existingtechnical solution. This is not limited in this application. Inaddition, the damping factor cannot be excessively small because asmaller damping factor causes severer system oscillation. Due to a valuelimitation of the damping factor, there is a value range of anadditional gain for the high frequency by the transimpedanceamplification circuit 202. As shown in FIG. 5, a solid line represents afrequency response curve of the optoelectronic detector 201, and adashed line is a combined frequency response curve of the transimpedanceamplification circuit 202 and the optoelectronic detector 201. Forexample, at a location a, a to-be-compensated difference does not exceedthe range of the additional gain for the high frequency by thetransimpedance amplification circuit 202, and therefore compensation maybe performed by using the transimpedance amplification circuit 202; andat a location b, a to-be-compensated difference exceeds the range of theadditional gain for the high frequency by the transimpedanceamplification circuit 202, and therefore complete compensation cannot beimplemented solely by using the transimpedance amplification circuit202. In this case, next-order compensation is needed.

The single-ended-to-differential converter 203 is configured to: convertthe voltage signal into a differential voltage signal, and send thedifferential voltage signal to the I/O interface 204 and the controller205.

The I/O interface 204 is configured to output the differential voltagesignal.

The controller 205 is configured to: generate a second control signalbased on the differential voltage signal, and send the second controlsignal to the transimpedance amplification circuit 202, where the secondcontrol signal is used to control the transimpedance amplificationcircuit 202 to perform transimpedance gain on the current signal.

Specifically, a signal processing process of the optical receiver 200 isas follows.

An optical signal detected by the optical receiver 200 first passesthrough the optoelectronic detector 201 for optoelectronic detection, togenerate a current signal, and the current signal is converted into avoltage signal after passing through the transimpedance amplificationcircuit 202. The transimpedance amplification circuit can provide afirst-order high frequency gain, and the gain is implemented inside thetransimpedance amplification circuit 202. As shown in FIG. 3, theresistance value of the variable resistance circuit 304 is adjusted, togenerate a peak gain at a gain frequency to compensate for insufficiencyof the bandwidth of the optoelectronic detector 201 (that is, provide ahigher gain at a high frequency in a passband range of thetransimpedance amplification circuit 202). Because the gain isimplemented inside the transimpedance amplification circuit 202 withoutintroducing additional noise, noise-free gain compensation can beimplemented for the high frequency. The high frequency herein is also afrequency that is higher than the upper cut-off frequency of theoptoelectronic detector 201.

The signal for which gain compensation is performed by thetransimpedance amplification circuit 202 is converted into adifferential signal by the single-ended-to-differential converter 203,and the differential signal is output by using the I/O interface 204.

Further, the controller 205 is configured to: adaptively generate thesecond control signal, and control the transimpedance amplificationcircuit 202 to perform transimpedance gain on the received currentsignal, to enable the transimpedance amplification circuit 202 toperform current-stage optimal compensation for the optoelectronicdetector 201. Three compensation possibilities: under-compensation,optimal compensation, and over-compensation are shown in FIG. 6.

Optionally, the second control signal that enables the transimpedanceamplification circuit 202 to perform the current-stage optimalcompensation is mainly generated in the following two manners:

(1) The controller 205 performs a plurality of times of samplingprocessing, and performs the following process in each time of samplingprocessing:

First, the controller 205 sends a control signal to the transimpedanceamplification circuit 202.

In this case, the transimpedance amplification circuit 202 generates,for the current signal, a transimpedance gain determined by the controlsignal, to obtain a voltage signal; and the voltage signal passesthrough the single-ended-to-differential converter 203, to obtain adifferential voltage signal.

Then, the controller 205 samples an upper level and a lower level of thereceived differential voltage signal, to obtain a value of a samplingpoint.

Finally, the controller 205 modifies the control signal based on apreset modification amount.

In other words, each time of sampling processing is performed for asignal that is obtained after different transimpedance gain, to obtain adifferent sampling point. A sampling point with a maximum value isselected from obtained sampling points, and a control signalcorresponding to the sampling point can enable the transimpedanceamplification circuit 202 to perform the current-stage optimalcompensation.

Therefore, after performing the plurality of times of samplingprocessing, the controller 205 is specifically configured to use, as thesecond control signal, the control signal corresponding to the samplingpoint with the maximum value in the plurality of sampling pointsobtained after the plurality of times of sampling processing.

(2) The controller 205 performs a plurality of times of detectionprocessing, and performs the following process in each time of detectionprocessing:

First, the controller 205 sends a control signal to the transimpedanceamplification circuit 202.

In this case, the transimpedance amplification circuit 202 generates,for the current signal, a transimpedance gain determined by the controlsignal, to obtain a voltage signal; and the voltage signal passesthrough the single-ended-to-differential converter 203, to obtain adifferential voltage signal.

Then, the controller 205 uses a first frequency as a boundary, andseparately detects energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency, to obtain an energydifference, where the first frequency is 0.28/Tb, and Tb is duration ofeach bit of the received differential voltage signal.

Finally, the controller 205 modifies the control signal based on apreset modification amount.

In other words, each time of detection processing is performed for asignal that is obtained after different transimpedance gain, to obtain adifferent energy difference. A minimum energy difference is selectedfrom obtained energy differences, and a control signal corresponding tothe energy difference can enable the transimpedance amplificationcircuit 202 to perform the current-stage optimal compensation.

Therefore, after performing the plurality of times of detectionprocessing, the controller 205 is specifically configured to use, as thesecond control signal, the control signal corresponding to the minimumenergy difference in the plurality of energy differences obtained afterthe plurality of times of detection processing.

It should be understood that the second control signal may be selectedat intervals. Because an execution time of the foregoing selectionprocess is very short compared with an interval time, servicetransmission is not affected. In addition, a compensation effect of thetransimpedance amplification circuit 202 varies with an environmentalchange, and the environmental change (such as a temperature change) is agradual process. Therefore, a control signal used during currentexecution may be modified for several times only in a relatively smallrange, and an optimal control signal is selected by using one of theforegoing methods (1) and (2). In this way, the execution time of theselection process can be effectively reduced.

Optionally, the optical receiver 200 further includes an equalizer 206.As shown in FIG. 7, the equalizer 206 is configured to: receive thedifferential voltage signal and a third control signal, perform gain onthe differential voltage signal based on the third control signal, andsend a differential voltage signal obtained after the gain to thecontroller and the I/O interface, where a frequency response value ofthe differential voltage signal within second bandwidth is greater thanthat within the first bandwidth, and any frequency in the secondbandwidth is higher than any frequency in the first bandwidth.

In this case, the controller 205 is further configured to: generate afourth control signal based on the differential voltage signal, and sendthe fourth control signal to the equalizer 206, where the fourth controlsignal is used to control the equalizer 206 to perform gain on thedifferential voltage signal.

Specifically, in this embodiment of this application, the differentialvoltage signal output by the single-ended-to-differential converter 203first passes through the equalizer 206. If gain compensation needs to befurther optimized, the equalizer 206 performs further gain on thedifferential voltage signal; and if gain compensation is optimal, theequalizer 206 does not perform processing on the signal, and isequivalent to a transmission circuit.

Further, the controller 205 is configured to: adaptively generate thefourth control signal, and control the equalizer 206 to perform gain onthe received differential voltage signal, to enable the equalizer 206 toperform optimal compensation for the optoelectronic detector 201. Theequalizer 206 may be an analog equalizer or a digital equalizer.

Optionally, the second control signal that enables the transimpedanceamplification circuit 202 to perform the optimal compensation and thefourth control signal that enables the equalizer 206 to perform theoptimal compensation are mainly generated in the following two manners:

(1) The controller 205 performs a plurality of times of first samplingprocessing, and performs the following process in each time of firstsampling processing:

sending, by the controller 205, a control signal to the transimpedanceamplification circuit 202;

sampling, by the controller 205, an upper level and a lower level of thereceived differential voltage signal, to obtain a value of a samplingpoint; and

modifying, by the controller 205, the control signal based on a presetmodification amount.

After performing the plurality of times of first sampling processing,the controller 205 uses, as the second control signal, a control signalcorresponding to a sampling point with a maximum value in a plurality ofsampling points obtained after the plurality of times of first samplingprocessing.

After sending the second control signal to the transimpedanceamplification circuit 202, the controller 205 further performs aplurality of times of second sampling processing, and performs thefollowing process in each time of second sampling processing:

sending, by the controller 205, a control signal to the equalizer 206;

sampling, by the controller 205, an upper level and a lower level of thereceived differential voltage signal, to obtain a value of a samplingpoint; and

modifying, by the controller 205, the control signal based on the presetmodification amount.

After performing the plurality of times of second sampling processing,the controller 205 uses, as the fourth control signal, a control signalcorresponding to a sampling point with a maximum value in a plurality ofsampling points obtained after the plurality of times of second samplingprocessing.

(2) The controller 205 performs a plurality of times of first detectionprocessing, and performs the following process in each time of firstdetection processing:

sending, by the controller 205, a control signal to the transimpedanceamplification circuit 202;

using, by the controller 205, a first frequency as a boundary, andseparately detecting energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency, to obtain an energydifference, where the first frequency is 0.28/Tb, and Tb is duration ofeach bit of the differential voltage signal; and

modifying, by the controller 205, the control signal based on a presetmodification amount.

After performing the plurality of times of first detection processing,the controller 205 uses, as the second control signal, a control signalcorresponding to a minimum energy difference in a plurality of energydifferences obtained after the plurality of times of first detectionprocessing.

After sending the second control signal to the transimpedanceamplification circuit 202, the controller 205 further performs aplurality of times of second detection processing, and performs thefollowing process in each time of second detection processing:

sending, by the controller 205, a control signal to the equalizer;

using, by the controller 205, the first frequency as a boundary, andseparately detecting energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency, to obtain an energydifference, where the first frequency is 0.28/Tb, and Tb is duration ofeach bit of the differential voltage signal; and

modifying, by the controller 205, the control signal based on the presetmodification amount.

After performing the plurality of times of second detection processing,the controller 205 uses, as the fourth control signal, a control signalcorresponding to a minimum energy difference in a plurality of energydifferences obtained after the plurality of times of second detectionprocessing.

It should be noted that if the obtained value of the sampling point ismaximum or the obtained energy difference is minimum when the equalizer206 does not perform gain on the differential voltage signal, itindicates that the transimpedance amplification circuit 202 has alreadyperformed optimal compensation for the optoelectronic detector 201, andthe equalizer 206 does not need to function; otherwise, it indicatesthat the equalizer 206 needs to function.

In addition, gain compensation by the transimpedance amplificationcircuit 202 is implemented inside the transimpedance amplificationcircuit 202 without introducing additional noise, but the equalizer 206introduces additional noise during compensation. Therefore, thetransimpedance amplification circuit 202 is adjusted preferentially.However, the equalizer 206 has an advantage of a wide compensationrange, and can perform compensation for a higher frequency compared withthe transimpedance amplification circuit 202. If the transimpedanceamplification circuit 202 cannot implement optimal compensation, theequalizer 206 may perform further compensation, to achieve an optimalcompensation effect.

Further, the second control signal and the fourth control signal may beselected at intervals. Because an execution time of the foregoingselection process is very short compared with an interval time, servicetransmission is not affected. In addition, compensation effects of thetransimpedance amplification circuit 202 and the equalizer 206 vary withan environmental change, and the environmental change (such as atemperature change) is a gradual process. Therefore, only a controlsignal used during current execution may be modified for several timesin a relatively small range, and an optimal control signal is selectedby using one of the foregoing methods (1) and (2). In this way, theexecution time of the selection process can be effectively reduced.

Another embodiment of this application provides a receiving method. Asshown in FIG. 8, the method includes the following steps:

801. An optical receiver converts a received optical signal into acurrent signal by using an optoelectronic detector, where bandwidth ofthe optoelectronic detector is lower than a system transmissionbandwidth requirement.

802. The optical receiver performs transimpedance gain on the currentsignal based on a first control signal, to obtain a voltage signal,where a frequency response value of the current signal within firstbandwidth is greater than that within the bandwidth of theoptoelectronic detector, and any frequency in the first bandwidth is notlower than an upper cut-off frequency of the optoelectronic detector.

803. The optical receiver converts the voltage signal into adifferential voltage signal, and generates a second control signal basedon the differential voltage signal, where the second control signal isused to control the optical receiver to perform transimpedance gain onthe current signal.

Optionally, solutions in which the optical receiver generates the secondcontrol signal based on the differential voltage signal are as follows:

(1) Perform a plurality of times of sampling processing, and use, as thesecond control signal, a control signal corresponding to a samplingpoint with a maximum value in a plurality of sampling points obtainedafter the plurality of times of sampling processing, where the followingprocess is performed in each time of sampling processing:

performing transimpedance gain on the current signal based on a controlsignal, to obtain the voltage signal, and converting the voltage signalinto the differential voltage signal; sampling an upper level and alower level of the differential voltage signal, to obtain a value of asampling point; and modifying the control signal based on a presetmodification amount.

(2) Perform a plurality of times of detection processing, and use, asthe second control signal, a control signal corresponding to a minimumenergy difference in a plurality of energy differences obtained afterthe plurality of times of detection processing, where the followingprocess is performed in each time of detection processing:

performing transimpedance gain on the current signal based on a controlsignal, to obtain the voltage signal, and converting the voltage signalinto the differential voltage signal; using a first frequency as aboundary, and separately detecting energy of the differential voltagesignal that is higher than the first frequency and energy of thedifferential voltage signal that is lower than the first frequency, toobtain an energy difference, where the first frequency is 0.28/Tb, andTb is duration of each bit of the differential voltage signal; andmodifying the control signal based on a preset modification amount. Inshort, in both the foregoing two solutions, the control signal ismodified, so that the received signal is in different statuses, and arelatively optimal control signal is selected by comparing thesestatuses.

Optionally, after the converting, by the optical receiver, the voltagesignal into a differential voltage signal, the method further includes:performing gain on the differential voltage signal based on a thirdcontrol signal, where a frequency response value of the differentialvoltage signal within second bandwidth is greater than that within thefirst bandwidth, and any frequency in the second bandwidth is higherthan any frequency in the first bandwidth. After the generating a secondcontrol signal, the method further includes: generating a fourth controlsignal based on a differential voltage signal obtained after the gain,where the fourth control signal is used to control the optical receiverto perform gain on the differential voltage signal.

In this case, solutions in which the optical receiver generates thesecond control signal and the fourth control signal based on thedifferential voltage signal are as follows:

(1) Perform a plurality of times of first sampling processing, and use,as the second control signal, a control signal corresponding to asampling point with a maximum value in a plurality of sampling pointsobtained after the plurality of times of first sampling processing,where the following process is performed in each time of first samplingprocessing:

performing transimpedance gain on the current signal based on a controlsignal, to obtain the voltage signal, and converting the voltage signalinto the differential voltage signal; sampling an upper level and alower level of the differential voltage signal, to obtain a value of asampling point; and modifying the control signal based on a presetmodification amount.

After generating the second control signal, the optical receiverperforms a plurality of times of second sampling processing, and uses,as the fourth control signal, a control signal corresponding to asampling point with a maximum value in a plurality of sampling pointsobtained after the plurality of times of second sampling processing,where the following process is performed in each time of second samplingprocessing:

performing gain on the differential voltage signal based on a controlsignal, to obtain the differential voltage signal obtained after thegain; sampling an upper level and a lower level of the differentialvoltage signal obtained after the gain, to obtain a value of a samplingpoint; and modifying the control signal based on the preset modificationamount.

(2) Perform a plurality of times of first detection processing, and use,as the second control signal, a control signal corresponding to aminimum energy difference in a plurality of energy differences obtainedafter the plurality of times of first detection processing, where thefollowing process is performed in each time of first detectionprocessing:

performing transimpedance gain on the current signal based on a controlsignal, to obtain the voltage signal, and converting the voltage signalinto the differential voltage signal; sampling an upper level and alower level of the differential voltage signal, to obtain a value of asampling point; and modifying the control signal based on a presetmodification amount.

After generating the second control signal, the optical receiverperforms a plurality of times of second detection processing, and uses,as the fourth control signal, a control signal corresponding to aminimum energy difference in a plurality of energy differences obtainedafter the plurality of times of second sampling processing, where thefollowing process is performed in each time of second detectionprocessing: performing gain on the differential voltage signal based ona control signal, to obtain the differential voltage signal obtainedafter the gain; using a first frequency as a boundary, and separatelydetecting energy of the differential voltage signal that is higher thanthe first frequency and energy of the differential voltage signal thatis lower than the first frequency, to obtain an energy difference, wherethe first frequency is 0.28/Tb, and Tb is duration of each bit of thedifferential voltage signal; and modifying the control signal based onthe preset modification amount.

This embodiment of this application is a method embodiment correspondingto the foregoing apparatus embodiment, implementation principles andachieved effects have been described in the foregoing embodiment, anddetails are not described in this embodiment of this application again.

Another embodiment of this application provides an optical receiver 900,and the optical receiver 900 may be applied to an ONU of a 10G PONsystem or a higher-rate PON system. As shown in FIG. 9, the opticalreceiver 900 includes an optoelectronic detector 901, a firsttransimpedance amplification circuit 902, a single-ended-to-differentialconverter 903, an equalizer 904, an I/O interface 905, and a controller906.

The optoelectronic detector 901 is configured to convert a receivedoptical signal into a current signal, where bandwidth of theoptoelectronic detector 901 is lower than a system transmissionbandwidth requirement.

Specifically, the optoelectronic detector 901 accounts for a largestproportion of costs in the optical receiver 900, and therefore componentcosts can be greatly reduced by using the low-bandwidth optoelectronicdetector 901. Correspondingly, there is a problem that a high-frequencysignal cannot be detected.

The first transimpedance amplification circuit 902 is configured to:receive the current signal, and perform transimpedance gain on thecurrent signal, to obtain a voltage signal.

The single-ended-to-differential converter 903 is configured to: convertthe voltage signal into a differential voltage signal, and send thedifferential voltage signal to the equalizer 904.

The equalizer 904 is configured to: receive the differential voltagesignal and a first control signal, perform gain on the differentialvoltage signal based on the first control signal, and send adifferential voltage signal obtained after the gain to the I/O interface905 and the controller 906, where a frequency response value of thedifferential voltage signal within first bandwidth is greater than thatwithin the bandwidth of the optoelectronic detector 901, and anyfrequency in the first bandwidth is higher than an upper cut-offfrequency of the optoelectronic detector 901.

The equalizer 904 herein may be an analog equalizer or a digitalequalizer.

The I/O interface 905 is configured to output the differential voltagesignal obtained after the gain.

The controller 906 is configured to: generate a second control signalbased on the differential voltage signal obtained after the gain, andsend the second control signal to the equalizer 904, where the secondcontrol signal is used to control the equalizer 904 to perform gain onthe differential voltage signal.

In this embodiment of this application, the equalizer 904 is used toimplement gain compensation for a high frequency. According to a featureof a wide compensation range of the equalizer 904, the equalizer 904 isenabled to perform compensation for the optoelectronic detector 901, toachieve an optimal effect. Compared with the previous embodiment withoutthe equalizer, this embodiment has an advantage of a wider range ofcompensation for the optoelectronic detector 901, and has a disadvantagethat more noise is introduced because gain compensation for the highfrequency is completely implemented by the equalizer.

Optionally, the second control signal that enables the equalizer 904 toperform current-stage optimal compensation for the optoelectronicdetector 901 is mainly generated in the following two manners:

(1) The controller 906 performs a plurality of times of samplingprocessing, and performs the following process in each time of samplingprocessing:

First, the controller 906 sends a control signal to the equalizer 904.

In this case, the equalizer 904 generates, for the differential voltagesignal, a gain determined by the control signal, to obtain thedifferential voltage signal obtained after the gain.

Then, the controller 906 samples an upper level and a lower level of thedifferential voltage signal obtained after the gain, to obtain a valueof a sampling point.

Finally, the controller 906 modifies the control signal based on apreset modification amount.

In other words, each time of sampling processing is performed for asignal that is obtained after different gain, to obtain a differentsampling point. A sampling point with a maximum value is selected fromobtained sampling points, and a control signal corresponding to thesampling point can enable the equalizer 904 to perform optimalcompensation.

Therefore, after performing the plurality of times of samplingprocessing, the controller 906 is specifically configured to use, as thesecond control signal, the control signal corresponding to the samplingpoint with the maximum value in the plurality of sampling pointsobtained after the plurality of times of sampling processing.

(2) The controller 906 performs a plurality of times of detectionprocessing, and performs the following process in each time of detectionprocessing:

First, the controller 906 sends a control signal to the equalizer 904.

In this case, the equalizer 904 generates, for the differential voltagesignal, a gain determined by the control signal, to obtain thedifferential voltage signal obtained after the gain.

Then, the controller 906 uses a first frequency as a boundary, andseparately detects energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency, to obtain an energydifference, where the first frequency is 0.28/Tb, and Tb is duration ofeach bit of the differential voltage signal.

Finally, the controller 906 modifies the control signal based on apreset modification amount.

In other words, each time of detection processing is performed for asignal that is obtained after different gain, to obtain a differentenergy difference. A minimum energy difference is selected from obtainedenergy differences, and a control signal corresponding to the energydifference can enable the equalizer 904 to perform optimal compensation.

Therefore, after performing the plurality of times of detectionprocessing, the controller 906 is specifically configured to use, as thesecond control signal, the control signal corresponding to the minimumenergy difference in the plurality of energy differences obtained afterthe plurality of times of detection processing.

Another embodiment of this application provides a receiving method. Asshown in FIG. 10, the method includes the following steps:

1001. An optical receiver converts a received optical signal into acurrent signal by using an optoelectronic detector, where bandwidth ofthe optoelectronic detector is lower than a system transmissionbandwidth requirement.

1002. The optical receiver performs transimpedance gain on the currentsignal, to obtain a voltage signal, and converts the voltage signal intoa differential voltage signal.

1003. The optical receiver performs gain on the differential voltagesignal based on a first control signal, to obtain a differential voltagesignal obtained after the gain, where a frequency response value of thedifferential voltage signal within first bandwidth is greater than thatwithin the bandwidth of the optoelectronic detector, and any frequencyin the first bandwidth is higher than an upper cut-off frequency of theoptoelectronic detector.

1004. The optical receiver generates a second control signal based onthe differential voltage signal obtained after the gain, where thesecond control signal is used to control the optical receiver to performgain on the differential voltage signal.

Optionally, generating a control signal with a relatively bestcompensation effect based on the differential voltage signal obtainedafter the gain is mainly performed in the following two methods:

(1) Perform a plurality of times of sampling processing, and use, as thesecond control signal, a control signal corresponding to a samplingpoint with a maximum value in a plurality of sampling points obtainedafter the plurality of times of sampling processing, where the followingprocess is performed in each time of sampling processing:

performing gain on the differential voltage signal based on a controlsignal, to obtain the differential voltage signal obtained after thegain; sampling an upper level and a lower level of the differentialvoltage signal obtained after the gain, to obtain a value of a samplingpoint; and modifying the control signal based on a preset modificationamount.

(2) Perform a plurality of times of detection processing, and use, asthe second control signal, a control signal corresponding to a minimumenergy difference in a plurality of energy differences obtained afterthe plurality of times of detection processing, where the followingprocess is performed in each time of detection processing:

performing gain on the differential voltage signal based on a controlsignal, to obtain the differential voltage signal obtained after thegain; using a first frequency as a boundary, and separately detectingenergy that is of the differential voltage signal obtained after thegain and that is higher than the first frequency and energy that is ofthe differential voltage signal obtained after the gain and that islower than the first frequency, to obtain an energy difference, wherethe first frequency is 0.28/Tb, and Tb is duration of each bit of thedifferential voltage signal; and modifying the control signal based on apreset modification amount.

The control methods in the foregoing plurality of embodiments are alladaptive feedback control manners. This application provides a pluralityof possible implementations, and any similar control solution shall fallwithin the protection scope of this application.

Further, in addition to the adaptive feedback control manners,equalization adjustment may further be controlled and implemented in aprogrammable analog or digital manner. An optical receiver in thissolution may include components similar to those included in any opticalreceiver shown in FIG. 2, FIG. 7, or FIG. 9. Functions of anoptoelectronic detector, a transimpedance amplification circuit, asingle-ended-to-differential converter, an equalizer, and an I/Ointerface are all the same as those in the foregoing embodiments, and anonly difference lies in that a controller does not need to receive adifferential voltage signal, and therefore does not perform samplingprocessing or detection processing on the differential voltage signal. Acorrespondence between an external environmental change and a controlsignal, such as a relationship between a temperature and a controlsignal, is estimated based on related information such as a simulationresult in a product design stage, and a corresponding control signal isdirectly selected based on an external temperature value. For reference,FIG. 11 is a schematic structural diagram of an optical receiverincluding components the same as those included in the optical receivershown in FIG. 2.

It should be understood that the relationship between an externalenvironmental change and a control signal may be pre-stored inside thecontroller; or may be stored in another driving component, where thedriving component controls the controller to work; or may be printed,where operating personnel control, based on the correspondence, thecontroller to work. This is not limited in this application.

According to the optical receiver provided in the plurality ofembodiments of this application, the optoelectronic detector whosebandwidth is lower than the system transmission bandwidth requirement isused, to greatly reduce costs of the optical receiver; and thetransimpedance amplification circuit and/or the equalizer are/is used,to remedy received signal deterioration caused by bandwidthinsufficiency, so that component costs are reduced while received signalquality is ensured.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

1. An optical receiver, comprising: an optoelectronic detector, theoptoelectronic detector configured to convert a received optical signalinto a current signal, wherein bandwidth of the optoelectronic detectoris lower than a system transmission bandwidth requirement; atransimpedance amplification circuit, the transimpedance amplificationcircuit configured to: receive the current signal and a first controlsignal; and perform transimpedance gain compensation for the currentsignal based on the first control signal to obtain a voltage signal,wherein a frequency response value of the current signal within firstbandwidth of the transimpedance amplification circuit is greater thanthat within the bandwidth of the optoelectronic detector, wherein anyfrequency in the first bandwidth is not lower than an upper cut-offfrequency of the optoelectronic detector, and wherein the first controlsignal is received from a controller; a single-ended-to-differentialconverter, the single-ended-to-differential converter configured to:convert the voltage signal into a differential voltage signal; and sendthe differential voltage signal to an I/O interface and the controller,wherein the first control signal is generated based on the differentialvoltage signal; and the I/O interface, the I/O interface configured tooutput the differential voltage signal.
 2. The optical receiveraccording to claim 1, further comprising the controller.
 3. The opticalreceiver according to claim 2, wherein the controller is configured toperform a plurality of sampling processing and perform the followingoperations in each of the plurality of sampling processing: sending acontrol signal to the transimpedance amplification circuit; sampling anupper level and a lower level of the received differential voltagesignal to obtain a value of a sampling point; and modifying the controlsignal based on a preset modification amount; and wherein afterperforming the plurality of sampling processing, the controller isconfigured to: use, as the first control signal, a control signalcorresponding to a sampling point with a maximum value in a plurality ofsampling points obtained after the plurality of sampling processing. 4.The optical receiver according to claim 2, wherein the controller isconfigured to perform a plurality of detection processing and performthe following operations in each of the plurality of detectionprocessing: sending a control signal to the transimpedance amplificationcircuit; using a first frequency as a boundary, and separately detectingenergy of the differential voltage signal that has a frequency higherthan the first frequency and energy of the differential voltage signalthat has a frequency lower than the first frequency to obtain an energydifference, wherein the first frequency is 0.28/Tb, and wherein Tb isduration of each bit of the differential voltage signal; and modifyingthe control signal based on a preset modification amount; and whereinafter performing the plurality of detection processing, the controlleris configured to: use, as the first control signal, a control signalcorresponding to a minimum energy difference in a plurality of energydifferences obtained after the plurality of detection processing.
 5. Theoptical receiver according to claim 1, further comprising an equalizer,wherein the equalizer is configured to: receive the differential voltagesignal from the single-ended-to-differential converter and a secondcontrol signal from the controller; perform gain on the differentialvoltage signal based on the second control signal; and send thedifferential voltage signal obtained after the gain to the controllerand the I/O interface, wherein a frequency response value of thedifferential voltage signal after the gain within second bandwidth ofthe equalizer is greater than that within the first bandwidth, andwherein any frequency in the second bandwidth is higher than anyfrequency in the first bandwidth.
 6. The optical receiver according toclaim 1, wherein the transimpedance amplification circuit comprises afixed resistor, a first transistor, a second transistor, a variableresistance circuit, and an output port, and wherein: the fixed resistorcomprises two ports, wherein one port is grounded and the other port isconnected to an emitter of the first transistor; a base of the firsttransistor is configured to receive an input signal, and a collector ofthe first transistor is connected to an emitter of the secondtransistor; a base of the second transistor is configured to receive abias voltage signal, and a collector of the second transistor isconnected to a first port of the variable resistance circuit, whereinthe bias voltage signal is used to adjust a gain for the input signal;the output port is located on a connecting line between the collector ofthe second transistor and the first port of the variable resistancecircuit; and the variable resistance circuit comprises three ports,wherein a second port of the variable resistance circuit is configuredto receive a control signal, wherein a third port of the variableresistance circuit is grounded, and wherein the control signal is usedto control a resistance value of the variable resistance circuit.
 7. Areceiving method, comprising: converting, by an optical receiver, areceived optical signal into a current signal by using an optoelectronicdetector, wherein bandwidth of the optoelectronic detector is lower thana system transmission bandwidth requirement; performing, by the opticalreceiver, transimpedance gain on the current signal based on a firstcontrol signal to obtain a voltage signal, wherein a frequency responsevalue of the current signal within first bandwidth is greater than thatwithin the bandwidth of the optoelectronic detector, and wherein anyfrequency in the first bandwidth is not lower than an upper cut-offfrequency of the optoelectronic detector; converting, by the opticalreceiver, the voltage signal into a differential voltage signal; andgenerating a first control signal based on the differential voltagesignal.
 8. The method according to claim 7, wherein generating the firstcontrol signal based on the differential voltage signal comprises:performing a plurality of sampling processing, and using, as the firstcontrol signal, a control signal corresponding to a sampling point witha maximum value in a plurality of sampling points obtained after theplurality of sampling processing, wherein the following process isperformed in each of the plurality of sampling processing: performingtransimpedance gain on the current signal based on a control signal toobtain the voltage signal, and converting the voltage signal into thedifferential voltage signal; sampling an upper level and a lower levelof the differential voltage signal to obtain a value of a samplingpoint; and modifying the control signal based on a preset modificationamount.
 9. The method according to claim 7, wherein generating the firstcontrol signal based on the differential voltage signal comprises:performing a plurality of detection processing, and using, as the firstcontrol signal, a control signal corresponding to a minimum energydifference in a plurality of energy differences obtained after theplurality of detection processing, wherein the following process isperformed in each of the plurality of detection processing: performingtransimpedance gain on the current signal based on a control signal toobtain the voltage signal, and converting the voltage signal into thedifferential voltage signal; using a first frequency as a boundary, andseparately detecting energy of the differential voltage signal that ishigher than the first frequency and energy of the differential voltagesignal that is lower than the first frequency to obtain an energydifference, wherein the first frequency is 0.28/Tb, and wherein Tb isduration of each bit of the differential voltage signal; and modifyingthe control signal based on a preset modification amount.
 10. The methodaccording to claim 7, further comprising: performing gain on thedifferential voltage signal based on a second control signal afterconverting, by the optical receiver, the voltage signal into thedifferential voltage signal, wherein a frequency response value of thedifferential voltage signal within second bandwidth is greater than thatwithin the first bandwidth, and wherein any frequency in the secondbandwidth is higher than any frequency in the first bandwidth; and aftergenerating the first control signal, generating the second controlsignal based on a differential voltage signal obtained after the gain.11. The method according to claim 10, wherein generating the firstcontrol signal based on the differential voltage signal comprises:performing a plurality of first sampling processing, and using, as thefirst control signal, a control signal corresponding to a sampling pointwith a maximum value in a plurality of sampling points obtained afterthe plurality of first sampling processing, wherein the followingoperations are performed in each of the plurality of first samplingprocessing: performing transimpedance gain on the current signal basedon a control signal to obtain the voltage signal, and converting thevoltage signal into the differential voltage signal; sampling an upperlevel and a lower level of the differential voltage signal to obtain avalue of a sampling point; and modifying the control signal based on apreset modification amount; and wherein generating the second controlsignal based on the differential voltage signal comprises: performing aplurality of second sampling processing, and using, as the secondcontrol signal, a control signal corresponding to a sampling point witha maximum value in a plurality of sampling points obtained after theplurality of second sampling processing, wherein the followingoperations are performed in each of the plurality of second samplingprocessing: performing gain on the differential voltage signal based ona control signal to obtain the differential voltage signal obtainedafter the gain; sampling an upper level and a lower level of thedifferential voltage signal obtained after the gain to obtain a value ofa sampling point; and modifying the control signal based on the presetmodification amount.
 12. The method according to claim 10, whereingenerating the first control signal based on the differential voltagesignal comprises: performing a plurality of first detection processing,and using, as the first control signal, a control signal correspondingto a minimum energy difference in a plurality of energy differencesobtained after the plurality of first detection processing, wherein thefollowing operations are performed in each of the plurality of firstdetection processing: performing transimpedance gain on the currentsignal based on a control signal to obtain the voltage signal, andconverting the voltage signal into the differential voltage signal;using a first frequency as a boundary, and separately detecting energyof the differential voltage signal that is higher than the firstfrequency and energy of the differential voltage signal that is lowerthan the first frequency to obtain an energy difference, wherein thefirst frequency is 0.28/Tb, and wherein Tb is duration of each bit ofthe differential voltage signal; and modifying the control signal basedon a preset modification amount; and wherein generating the secondcontrol signal based on the differential voltage signal comprises:performing a plurality of second detection processing, and using, as thesecond control signal, a control signal corresponding to a minimumenergy difference in a plurality of energy differences obtained afterthe plurality of second detection processing, wherein the followingoperations are performed in each of the plurality of second detectionprocessing: performing gain on the differential voltage signal based ona control signal to obtain the differential voltage signal obtainedafter the gain; using the first frequency as a boundary, and separatelydetecting energy of the differential voltage signal that is higher thanthe first frequency and energy of the differential voltage signal thatis lower than the first frequency, to obtain an energy difference,wherein the first frequency is 0.28/Tb, and wherein Tb is duration ofeach bit of the differential voltage signal; and modifying the controlsignal based on the preset modification amount.
 13. An optical receiver,comprising an optoelectronic detector, a transimpedance amplificationcircuit, a single-ended-to-differential converter, and an I/O interface,wherein: the optoelectronic detector, the transimpedance amplificationcircuit, the single-ended-to-differential converter, and the I/Ointerface are connected sequentially; bandwidth of the optoelectronicdetector is lower than a system transmission bandwidth requirement; thetransimpedance amplification circuit is configured to receive a controlsignal generated based on a differential voltage signal outputted by thesingle-ended-to-differential converter; and a frequency response valueof a current signal within first bandwidth of the transimpedanceamplification circuit is greater than that within the bandwidth of theoptoelectronic detector, and any frequency in the first bandwidth is notlower than an upper cut-off frequency of the optoelectronic detector.14. An optical receiver according to claim 13, further comprising acontroller, the controller configured to generate the control signalgenerated based on a differential voltage signal outputted by thesingle-ended-to-differential converter.
 15. An optical receiveraccording to claim 13, further comprising an equalizer, wherein thesingle-ended-to-differential converter and the I/O interface areconnected via the equalizer.
 16. The optical receiver according to claim13, wherein the transimpedance amplification circuit comprises a fixedresistor, a first transistor, a second transistor, a variable resistancecircuit, and an output port, and wherein: the fixed resistor comprisestwo ports, wherein one port is grounded and the other port is connectedto an emitter of the first transistor; a base of the first transistor isconfigured to receive an input signal, and a collector of the firsttransistor is connected to an emitter of the second transistor; a baseof the second transistor is configured to receive a bias voltage signal,and a collector of the second transistor is connected to a first port ofthe variable resistance circuit, wherein the bias voltage signal is usedto adjust a gain for the input signal; the output port is located on aconnecting line between the collector of the second transistor and thefirst port of the variable resistance circuit; and the variableresistance circuit comprises three ports, wherein a second port of thevariable resistance circuit is configured to receive a control signal,wherein a third port of the variable resistance circuit is grounded, andwherein the control signal is used to control a resistance value of thevariable resistance circuit.